Electric heating unit.



B=` FALKENBERG. ELECTRIC HEATING UNIT.

APPLICATION FILED MAY 21, 191,2.

UNITED sTATns PATENT onnion BJARNE FALKENBERG, OF ONTARIO, CALIFORNIA, ASSIGNOR TO PACIFIC ELECTRIC HEATING COMPANY, OF ONTARIO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

ELECTRIC HEATING UNIT.

Speccation of Letters Patent.

Patented July 22, 1913.

.which the following is a specification.

' This invention relates to electric heating units and the main object of the invention is to so construct the unit that it is selfcontained and capable of operating as a single unit or of being assembled with one pressed metal with fewestv possible parts and with minimum thickness, -thereby securing maximum heat delivery to the surface of the heater, and to provide a constructionwhereby there will be a minimum warping action. p

Another object is to so construct the unit that the electrical element maybe quickly removed 'and replaced if it becomes necessar I further object is to construct the electric element, consisting of the core and resist-ance wire, as a flexible element whereby it may yield in all directions and conform to any deviation from a plane surface.

Referring to the drawingsz-Figure 1 is a side elevation of the device. Fig. 2 is a longitudinal section through the device on line 00L-m2 Fig. 3. Fig. 3 is a section on line :ca -m3 Fig. 2. Fig. 4 is a perspective of the retaining plate. Fig. 5 is a perspective view of a ortion of one of the insulating sheets. Fig. 6 is a perspective of th'e electrical element, including thev core on which it is wound. Fig. 7 is a perspective of the inverted outer late. Fig. 8 is an elevation of a portion o the core of the electrical element.

The electric unit consists of a thin exible sheet of mica 1 as shown in Fig. 6 wound with resistance wire 2. At each end the I mca sheet 1 has lateral lugs 3 which pro- ]ect be ond the wire'2 and each end of the mica sieet 1s perforated and the ends 4.- of the wire extend therethrough. rlfhe electric element thus `formed is perfectly flexible and capable of bending in all directions and lies within the outer plate 5 which has two downturned ends 6 with perforations 7 enabling attachment of the same to any supporting device desired and having depending side flanges 8 with lugs 9. A sheet of mica l0 lies next to the outer plate 5 to insulatethe wire 2 therefrom and on the other side of the electric unit is a sheet of mica 11 which insulates the wire 2 from a retaining platel 12 which lies within the outer plate 5. The outer plate 5 and retaining plate 12 are both preferably formed of sheet metal and the retainin plate 12 has depending iianges 13. The anges 8 of the outer plate and the flanges 18 of the retaining plate are both tapered toward each end, as clearly shown, for the. purpose of stiffening the plates endwise and preventing warping. The lugs 9 of the outer plate are bent over the flanges 13 of the retaining plate and the latter is thus firmly held in position and holds the electric .unit in close contact against the outer plate with yonly the intervening thin sheet of insulating mica between. The retaining plat-e 12 has comparatively large perforations 14 in its ends, each perforation permitting the adjacent wire end l to pass therethrough without coming in contact with the material forming the plate and thereby dispensing with insulation.

Whenever it is desired to replace the electric unit the lugs 9 may be bent back to release the retaining plate 12, whereupon the electric unit may be readily removed and replaced with a new one, after which the retaining plate is again placed in position and the lugs 9 bent back over the flanges 13.

The core 1 may be formed with notches 15 in its side edges, which will engage the coils 2 and hold the coils in proper position, preventing any possibility of short circuiting, in addition to holding them uniformly spaced, giving a better distribution of heat.

The electric element being eXible, bends and accommodates itself to'any departure from a plane surface of the walls between which it is confined.

lVhat l claim is v 1. An electric heating unit comprising an outer plate of thinfmaterial with depending stifi'ening flanges, an electrical unit comprising a coil of resistance wire below said outer plate, and a retaining plate with depending stilfcning flanges secured to the outer plate means for securing said retaining plate in position.

3. An outer plate with depending flanges, each flange being tapered toward each end, an electrical resistance beneath said plate, a retaining plate With depending fianges lying beneath said resistance and means for holding said retaining plate in position.

Je. An outer plate with downturned ends and with depending side fianges, electrical resistance below said plate, a retaining plate below said resistance and holding the same against said plate and means holding the retaining plate in position.

5. An outer plate with depending flanges having lugs, a retaining plate having depending flanges, said lugs being bent over the latter flanges, and electrical resistance between said retaining plate and the first plate.

6. An outer plate with depending flanges, a flat core of insulating material, wire wound on said core, said wire-wound core being below Asaid plate, a sheet of insulation on each sideof the wire, a retaining plate below said wire-wound core and provided with orifices through which the wire passes, and lugs on the flanges of the outer plate bent over the flanges of the retaining plate.

7. An outer plate with depending flanges, a- Hat core of insulating material, wire wound on said core, said Wire-'wound core being below said late, a sheet of insulation` holding said plates and resistance close together.

9. An electric heating unit comprising two fiat plates, a thin flat electrical resistance between said plates, and means detachably holding said plates closely against the resistance, the outer plate having depending end Hanges which project below the other elements and support the unit.

In testimony whereof I have hereunto set my hand at Ontario, California, this 22nd day of April, 1912.

P. H. BOOTH, FRANKLIN Boo'rH. 

